Need hel on XOR & #

[Paul Haug]

I am trying to xor two bytes together with the results in one of the two bytes.
I have spent consertable time looking at GCB documentation and see it is mentioned but cannot find an example.
Also is there a way to flip a port bit with one instruction ?
Many thanks to all on this forum for previous help also

Paul

[Chris Roper]

You can't do it in one instruction on the PIC12/16/18 devices like you can on the PIC32 as they do not have a toggle register.

But it can be done in one line of GCBASIC code
The following example should help:

MyPORT = MyPORT XOR MyMask

Where MyPORT is the Port you ar interested in, eg. PortB
and MyMASK is the Port pin or Pins eg. 7

Working example Flashes PortB.7

#chip 16F877a

Do
  PortB = PortB XOR b'10000000'
  wait 100 ms
Loop

Chears
Chris

[Paul Haug]

Thanks Chris,
Both of those example are good for my task and I tested to see them work.
I have this thing about the need to understand code in detail, so I will lookup the FnLSL function to clarify to myself how your code works. It's beautiful.

[Chris Roper]

FnLSL is designed to emulate the C function <<
So where in C or C++ code you see
MyVal = 1<<4

You can replace it in GCBASIC with
MyVal = FnLSL(1, 4)

Hope that helps.

[Chris Roper]

Actually GCBASIC has got a Toggle instruction, as '=!' returns the logical inverse.
So we can create a Macro that gives you the toggle command you need:

'
' Flash an LED connected to PortB.4
'
#Chip 16F877A

#define MyLED PortB.4

Dir MyLED Out

Do
  Toggle(MyLED)
  wait 100 ms
loop

Macro Toggle(MyPIN)
  MyPIN =! MyPIN
End Macro

Cheers
Chris

[Paul Haug]

Even better. Thanks.
.
will use like this, no need for the macro now to keep it simple.
portb.3 =! portb.3 ; The toggle cmnd is =!